1. Field of the Invention
The present invention relates to polymers resulting from polymerizing ethylenically unsaturated esters derived from 3,4-epoxy-1-butene or epoxybutene. The polymers may be homopolymers or copolymers containing other ethylenically unsaturated monomers. The polymers of the invention may be used in a variety of coating compositions such as inks, adhesives, paints, and films.
2. Description of the Related Art
The ring opening chemistry of epoxides is well known. (Evans et al., J. Chem. Soc. 248 (1949)). Opening an epoxide ring with a nucleophile can create one hydroxyl moiety or, depending on reaction conditions, two hydroxyl moieties. The hydroxyl groups can undergo further reaction. The hydroxyl groups can, for example, be converted to esters by reaction with carboxylic acids. Hydroxyl groups can also be converted to acetoacetic esters. (Clemens, R. J., Chemical Reviews, 86:241-318 (1986); Witzeman, J. S., U.S. Pat. No. 5,051,529 (1991)).
Reacting an epoxide group with an acid anhydride can yield a disubstituted ester derivative (U.S. Pat. No. 5,623,086). Reacting an epoxide with an alcohol results in the formation of a hydroxy ether and is well known in the literature. The remaining hydroxyl group may be further derivatized using, for example, carboxylic acids or anhydrides to form esters using methods well known to those skilled in the art.
The ring opening reaction of 3,4-epoxy-1-butene or epoxybutene with hydroxide base yields an ethylenically unsaturated diol, 3-butene-1,2-diol, having the following structure: 
The two hydroxyl moieties provide a possible means by which further functionality may be added to the polymer. For example, U.S. Pat. No. 2,504,082 describes the synthesis of the propenyl ester of 1-hydroxy-2-methoxy-3-butene. U.S. Pat. No. 4,916,255 describes the synthesis of the methacrylate ester of 1-hydroxy-2-methoxy-3-butene.
However, the polymerization of ethylenically unsaturated esters such as allyl esters has proven difficult. Homopolymerization of allyl esters such as allyl acetate is sluggish and results in a low molecular weight polymer. Allyl esters will also only copolymerize with a few selected unsaturated monomers such as vinyl esters or maleic anhydride. (C. E. Schildknecht, Allyl Compounds and Their Polymers, Wiley-Interscience, 1973).
Similarly, only a few monomers are known that will copolymerize effectively with vinyl esters. For a number of applications, particularly coatings, poly(vinyl acetate) needs to be modified with other monomers to provide a lower glass transition temperature, Tg. Vinyl esters such as vinyl neodecanoate have been shown to be useful in lowering the Tg of poly(vinyl acetate), but are expensive. Other vinyl esters that have also been shown useful in reducing the Tg of poly(vinyl acetate) include butyl acrylate and 2-ethyl hexyl acrylate. Copolymers of vinyl acetate and butyl acrylate are heterogeneous due to the differences in reactivity (e.g., C. Pichot, M. F. Llauro, Q. T. Pham, J. Polym. Sci.: Polym. Chem. Ed., 19,2619-2633 (1981)). However, monomers that will copolymerize well with vinyl esters such as vinyl acetate and result in polymers with functional groups available for post-polymerization are not known in the art.
Therefore, a need exists in the art for functionalized ethylenically unsaturated esters which may be used as monomers and undergo facile polymerization. Moreover, the needed monomers should not only be able to form high molecular weight polymers but also be able to copolymerize with a variety of other ethylenically unsaturated monomers. It would also be desirable that such a funtionalized ethylenically unsaturated monomer contain functionality capable of surviving polymerization and undergoing further post-polymerization reaction.
The invention provides a polymer formed by the polymerization of a monomer of formula (I): 
In formula (I), at least one of R1 and R2 is an ester group. The monomer of formula (I) may be homopolymerized. The monomer may also be copolymerized with other ethylenically unsaturated monomers. The invention also provides coating compositions containing such polymers.
The invention further provides a method of making a polymer containing a monomer of formula (I). The method involves the polymerization, such as free-radical polymerization, of a monomer of formula (I) with either itself or with another ethylenically unsaturated monomer.
The invention further provides a monomer of formula (I) of which at least one of R1 and R2 is an acetoacetyl group as well as monomers of formula (I) of which R1 is a methyl group and R2 is either an acetoacetyl or an acetyl group.
The invention still further provides a enamine functional polymer resulting from the reaction of an amine and the polymerization product of a monomer of formula (I) and, optionally, an ethylenically unsaturated monomer. In formula (I), at least one of R1 and R2 is an acetoacetyl group. The invention also provides a method of making the enamine functional polymers.
One embodiment of the invention is a polymer resulting from polymerization of a monomer of formula (I): 
and, optionally, an ethylenically unsaturated monomer. Mixtures of these monomers together or with other ethylenically unsaturated monomers may be used to prepare polymers of the invention. Preferably, the polymerization is a free-radical polymerization.
In formula (I), R1 and R2 are, independently, hydrogen, a C1-C24 alkyl group, an aromatic or heteroaromatic group, a C3-C8 cycloalkyl or C2-C7 heterocycloalkyl group, or a xe2x80x94C(O)R3 group. R3 is a C1-C24 alkyl group, an aromatic or heteroaromatic group, a C3-C8 cycloalkyl or C2-C7 heterocyclic group, or a xe2x80x94CH2xe2x80x94C(O)xe2x80x94R4 group where R4 is a C1-C6 alkyl group. In the monomers of formula (I), at least one of R1 and R2 is a xe2x80x94C(O)R3 group forming an ester. Preferably, when R1 and R2 both a xe2x80x94C(O)R3 group, R3 is a xe2x80x94CH2xe2x80x94C(O)xe2x80x94R4 where R4 is methyl group, i.e. an acetoacetyl group. When R1 is a methyl group, preferably, R2 is either an acetyl group or an acetoacetyl group.
The alkyl group of R1, R2 and R3 may be a linear or branched alkyl group. Preferably, the alkyl group is a C1-C12 alkyl group. More preferably, the alkyl group is, for example, a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, neopentyl or hexyl group. The alkyl group of R4 may also be a linear or branched alkyl group. Preferably, R4 is a C1-C4 alkyl group. More preferably, R4 is, for example, a methyl, ethyl, or propyl group.
Preferred aromatic and heteroaromatic groups described here include, but are not limited to, phenyl, furanyl, pyrrolyl, isopyrrolyl, thienyl, napthyl, pyridinyl, pyranyl, and benzyl. Preferred cycloalkyl groups described here are C3-C6 cycloalkyl groups. More preferably, the cycloalkyl group is, for example, a cyclopropyl, cyclopentyl, or cyclohexyl group. The heterocycloalkyl groups described here are preferably C2-C5 heterocycloalkyl groups. More preferably, the heterocycloalkyl groups is, for example, an oxiranyl, aziridinyl, imidazolidinyl, pyrazolidinyl, piperidinyl, piperazinyl, or morpholinyl group.
In addition, an alkyl group, aromatic or heteroaromatic group, or a cycloalkyl or heterocyclic group may be substituted with groups such as, but not limited to, nitro, bromo, chloro, fluoro, hydroxy, and alkoxy groups. An aromatic or heteroaromatic group or cycloalkyl or heterocycle may also be substituted with a C1-C4 alkyl group. Possible heteroatoms for heteroaromatic groups include nitrogen, oxygen, and sulfir.
The ethylenically unsaturated monomer can be any monomer which contains at least one ethylenically unsaturated group allowing it to be copolymerized with monomers of formula (I). Such monomers include, for example, allylic compounds, vinylic compounds, styrenic compounds, xcex1,xcex2-unsaturated compounds, alkenes, acrylic compounds and the like. Examples of suitable ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, vinyl pivalate, vinyl neodecanoate, vinyl neononanoate, vinyl crotonate, vinyl 2-ethyl hexanoate, vinyl propionate, 4-vinyl-1,3-dioxolan-2-one; ethylene, epoxy butene; vinyl chloride, vinyl methacrylate; allyl alcohol, allyl chloride, allyl acetate, allyl methacrylate, di-allylmalonate; dimethyl maleate, diethyl maleate, di-n-butyl maleate, di-octyl maleate, maleic anhydride; 3-butene-1,2-diacetate, 3-butene-1,2-dipropionate, 3-butene-1,2-dibutyrate, 3-butene-1,2-dibenzoate; dimethyl itaconate, itaconic anhydride; crotonic acid and its esters, for example, C1-C18 alkyl crotonates; acrylonitrile; acrylamide, methacrylamide, butyl acrylamide, ethyl acrylamide; acrylic acid; methyl acrylate, ethyl acrylate, ethylhexyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, hydroxy ethyl acrylate, hydroxy propyl acrylate, lauryl acrylate, octyl acrylate, iso-octyl acrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, ethylhexyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, hydroxy ethyl methacrylate, hydroxy propyl methacrylate, octyl methacrylate, glycidyl methacrylate, carbodiimide methacrylate, methoxybutenyl methacrylate, isobomyl methacrylate, hydroxybutenyl methacrylate, isopropenyl methacrylate, iso-octyl methacrylate, cylcoaliphaticepoxy methacrylate; ethylformamide; styrene and xcex1-methyl styrene. Preferably the ethylenically unsaturated monomer is the vinyl ester, vinyl acetate.
Another embodiment of the invention is a method of making a polymer of the invention. The method involves polymerizing, preferably under free-radical polymerization conditions, a monomer of formula (I) as described above and, optionally, an ethylenically unsaturated monomer, also as described above. Free radical polymerization of monomer (I) is achieved under conditions known by those skilled in the art. The polymerization is conducted in the presence of a free radical generating initiator. The free radical polymerization process may be a bulk, solution, emulsion, or suspension process. Preferably, the free radical polymerization process is a semi-batch solution or emulsion process.
The free radical generating initiator may be any conventional free radical polymerization initiator. Examples of suitable initiators include, but are not limited to, azo(bis isobutyronitrile), benzoyl peroxide, di-t-butyl peroxide, t-butyl peroctoate, t-amyl-peroxy-2-ethyl hexanoate, and the like. Quantitative conversion of monomer (I) to the corresponding polymer can be improved by using a more active free radical initiator, i.e. one with a shorter half-life, conducting the polymerization at a higher temperature, or using a higher concentration of initiator.
If a solvent is used to carry out the polymerization process, solvents which can solubilize both monomer (I) and the resulting polymer are preferred. Examples of suitable solvents include, but are not limited to, xylene, toluene, methyl amyl ketone, ethyl ethoxy propionate, propylene glycol monomethyl ether, ethylene glycol butyl ether, and the like. Preferably, the solvent is either a glycol ether or a glycol ether ester.
Polymerization of a monomer of formula (I), optionally with another ethylenically unsaturated monomer, occurs through the ethylenically unsaturated group of each monomer. The polymer of the invention may contain at least one pendant functional moiety through which further chemistry can be conducted. The pendant functional moiety may be any moiety which can undergo further reactions including, for example, reacting with crosslinkers to form thermoset materials. Preferably, the pendant functional moiety is a hydroxyl group, an acetoacetoxy group, or a combination thereof.
A crosslinker used with a polymer of the invention may be any material capable of reacting with an active hydrogen containing resin and include those well known in the art. Preferably, the resin is a urea-formaldehyde, a melamine-formaldehyde, or an isocyanate resin.
Polymers of the invention are generally thermoset polymers and can be used in a variety of coating compositions such as architectural coatings, maintenance coatings, industrial coatings, automotive coatings, textile coatings, inks, adhesives, and coatings for paper, wood, and plastics, and the like as described, for example, in U.S. Pat. No. 5,539,073 incorporated in its entirety herein by reference. Accordingly, the invention relates to such coating composition containing a polymer of the invention. The coating composition may be solvent-based or water-based. The polymers of the invention may be incorporated in those coating compositions in the same manner as known polymers and used with the conventional components and or additives of such compositions. The coating compositions may be clear or pigmented.
Upon formulation, a coating composition containing a polymer of the invention may then be applied to a variety of surfaces, substrates, or articles, e.g., paper, plastic, steel, aluminum, wood, gypsum board, or galvanized sheeting (either primed or unprimed). The type of surface, substrate, or article to be coated generally determines the type of coating composition used. The coating composition may applied using means known in the art. For example, a coating composition may be applied by spraying or by coating a substrate. In general, the coating may be dried by heating but preferably is allowed to air dry. Advantageously, a coating employing a polymer of the invention may be thermally or ambiently cured. As a further aspect, the present invention relates to a shaped or formed article which has been coated with a coating compositions of the invention.
A coating composition according to the invention may comprise a polymer of the invention, water, a solvent, a pigment (organic or inorganic) and/or other additives and fillers known in the art For example, a latex paint composition of the invention may comprise a polymer of the invention, water, a pigment and one or more additives or fillers used in latex paints. Such additives or fillers include, but are not limited to, leveling, rheology, and flow control agents such as silicones, fluorocarbons, urethanes, or cellulosics; extenders; reactive coalescing aids such as those described in U.S. Pat. No. 5,349,026; flatting agents; pigment wetting and dispersing agents and surfactants; ultraviolet (UV) absorbers; UV light stabilizers; tinting pigments; extenders; defoaming and antifoaming agents; anti-settling, anti-sag and bodying agents; anti-skinning agents; anti-flooding and anti-floating agents; fungicides and mildewcides; corrosion inhibitors; thickening agents; plasticizers; reactive plasticizers; curing agents; or coalescing agents. Specific examples of such additives can be found in Raw Materials Index, published by the National Paint and Coatings Association, 1500 Rhode Island Avenue, NW, Washington, D.C. 20005.
Another embodiment of the invention is a monomer of formula (I): 
In formula (I), R1 is a C1-C24 alkyl group or an aromatic or heteroaromatic group as defined above and R2 is a xe2x80x94C(O)R3 group where R3 is a C1-C24 alkyl group, an aromatic or heteroaromatic group, a C3-C8 cycloalkyl or C2-C7 heterocyclic group; or a xe2x80x94CH2xe2x80x94C(O)xe2x80x94R4 group where R4 is a C1-C6 alkyl group, all as defined above. Preferably, both R1 and R2 are a xe2x80x94C(O)xe2x80x94CH2xe2x80x94C(O)xe2x80x94R4 group where R4 is methyl group, i.e. both R1 and R2 are an acetoacetyl group. In another preferred embodiment, R1 is a methyl group and R2 is either an acetyl group or an acetoacetyl group. Examples of suitable monomers of formula (I) include, but are not limited to, 1-acetoxy-2-methoxy-3-butene, 1-acetoacetoxy-2-methoxy-3-butene, 3-butene-1,2-dipropionate, 1,2-diacetoxy-3-butene, 3-butene-1,2-diol monoacetate, 3-butene-1,2-diacetate, and 1,2-bisacetoacetate-3-butene.
Another embodiment of the invention relates to derivatizing a polymer of the invention to form an enamine functional polymer. In an enamine functional polymer, the enamine functionality serves to stabilize the acetoacetoxy-groups and protect them from hydrolysis. Enamine-functional polymers have been described in Moszner et al., Polymer Bulletin 32, 419-426 (1994); European patent Application No. 0 492 847 A2; U.S. Pat. No. 5,296,530; U.S. Pat. No. 5,484,849; U.S. Pat. No. 5,484,975; and U.S. Pat. No. 5,525,662. These documents are incorporated here by reference.
An enamine functional polymer according to the invention results from the reaction of an amine and an acetoacetoxy functionalized polymer. The acetoacetoxy functionalized polymer is the polymerization product of a monomer of formula (I): 
and, optionally, an ethylenically unsaturated monomer. In formula (I), R1 and R2 are, independently, hydrogen, a C1-C24 alkyl group, an aromatic or heteroaromatic group, a C3-C8 cycloalkyl or C2-C7 heterocycloalkyl group, or a xe2x80x94C(O)R3 group. R3 is a C1-C24 alkyl group, an aromatic or heteroaromatic group, a C3-C8 cycloalkyl or C2-C7 heterocyclic group, or a xe2x80x94CH2xe2x80x94C(O)xe2x80x94R4 group where R4 is a C1-C6 alkyl group. In the acetoacetoxy functional polymer, in the monomers of formula (I), at least one of R1 and R2 is an acetoacetyl group. The acetoacetoxy functionalized polymer has one or more pendant acetoacetoxy moieties.
According to the invention, enamine functional polymers may be prepared by reacting an amine with an acetoacetoxy functionalized polymer as described above. The reaction stoichiometry uses at least one molar equivalent of amino (NH) groups to acetoacetoxy groups. The amine may be any amine which upon reaction with the pendant acetoacetoxy moiety or moieties of the acetoacetoxy functionalized polymer forms an enamine group. Suitable amines include, for example, ammonia, primary amines and secondary amines. Preparation of enamines from acetoacetoxy groups are described in U.S. Pat. Nos. 5,296,530, 5,484,975, and 5,525,662 which are incorporated here by reference.
Though the reaction is rapid, an equilibrium exists between the enamine product and the acetoacetoxy/NH reactants. Although the reaction may be conducted at room temperature, the rate of enamine formation increases with temperature. Due to the equilibrium, however, an enamine functionalized polymer of the invention may have both enamine and acetoacetoxy groups.
Enamine functional polymers or copolymers may also be prepared by polymerization of enamine functional monomers. An enamine functional monomer may be prepared by the reaction of an acetoacetoxy monomer with an amine such as those described above. Polymerization of the resulting enamine functional monomer will produce an enamine functional polymer. This method of enamine polymer preparation is described Moszner et al., Polymer Bulletin 32, 419-426 (1994).